Topic label explains problem. Few more people have this issue. I see this on ION Beta 3.
forum topic: http://openelec.tv/forum/65-storage/14727-xs35gt-usb-harddisks-autoreconnects-after-qsafely-removeq#33476
Err. Could you test and report if this is fixed in this build?
It works for me on USB storage devices.
i think this should be fixed now, if this problem still exist in our next beta please open a new issue report.